1. Field of the Invention
The present invention relates to a sealed compressor driven by a motor used in a refrigerating machine or an air conditioning system.
2. Description of the Related Art
A conventional sealed compressor driven by a motor is provided with a compressor unit installed at an upper portion in a cylindrical drum which is a main body of a hermetically sealed vessel and a motor unit installed on the lower side of the compressor unit for driving the compressor unit. A refrigerant returned from a refrigerating cycle of a refrigerator, an air conditioner or the like is sucked from a refrigerant suction pipe installed at an upper portion of the cylindrical drum, compressed by the compressor unit and thereafter temporarily delivered from a refrigerant discharge port installed at a central portion of the compressor unit into the hermetically sealed vessel A portion of gas filled in the cylindrical drum reaches an upper portion of a rotor from a gap of a coil end present on the side of the compressor unit of a stator constituting the motor. Other portion of the gas reaches a lower portion of the motor after passing through a refrigerant gas passage installed at a steel plate portion of the outer configuration of the stator and thereafter flows into an upper space of the rotor after passing through a clearance between the stator and the rotor. Thereafter, the gas which has flowed into the upper space of the rotor is delivered from a discharge pipe installed to project inwardly from an inner wall of the cylindrical drum to the refrigerating cycle.
At this occasion, the gas which has flowed from the gap of the coil end on the compressor unit side of the stator into the upper space of the rotor is a mist-like gas including a large amount of refrigerator oil since it is the gas immediately after having been delivered from the compressor unit and it is constituted that the mist-like refrigerant gas including a large amount of the refrigerator oil is delivered to the refrigerating cycle via the discharge pipe while being stirred by an upper portion of the rotor.
Further, JP-A-63-21385 discloses a sealed compressor driven by a motor which reduces a refrigerator oil delivered to a refrigerating cycle A refrigerant delivered from an upper portion of a scroll compressor passes from an upper portion of a compressor unit through a refrigerant passage installed between the compressor unit and a hermetically sealed vessel, passes through a flow guideplate installed between a block provided with a main bearing for receiving thrust load of a orbital scroll and a stator of a motor and is guided from the compressor unit to a lower portion of the stator. In the procedure, an oil separator is installed between the cylindrical drum and the stator and therefore, the refrigerant which has passed through the oil separator is separated of refrigerator oil and the refrigerator oil is returned to an oil storage at a lower portion of the hermetically sealed vessel. In the meantime, the refrigerant separated of the refrigerator oil passes through a second oil separator installed between the cylindrical drum and the stator, is guided to a lower portion of the block while being separated of oil and is delivered to the refrigerating cycle from a discharge pipe installed between the block of the cylindrical drum and the stator.
According to the flow path of the refrigerant in the conventional sealed compressor driven by a motor, there pose following problems, explained below. Generally, inside of a sealed compressor driven by a motor is filled with a lubricant (refrigerator oil) in order to promote sliding efficiency and preventing wear of parts by reducing frictional force between parts at a compressor unit and a bearing portion.
Almost all of the refrigerator oil is stored at a bottom portion of inside of a hermetically sealed vessel, particularly, an oil storage portion, passes through an oil feed path installed in a shaft a lower portion of which is dipped in the oil storage portion and lubricates a main bearing portion, an intermediary between a orbital scroll and a fixed scroll in the compressor unit and an intermediary between a front end of a scroll lap and a endplate. The refrigerator oil which has passed through the oil feed path in the shaft and fed to the bearing portion, passes through a bearing clearance portion and is again stored at the bottom portion of the vessel.
In the meantime, the refrigerator oil fed to the compressor unit is delivered from a discharge port into the vessel similar to the refrigerant and again stored at the bottom portion of the vessel. However, a portion of the refrigerator oil delivered from the discharge port, is delivered in a mist-like form and therefore, almost all of the mist-like refrigerant oil passes through a passage similar to the above-described flow path of the refrigerant, discharged from the discharge pipe into the refrigerating cycle along with the refrigerant, passes again through a suction pipe and is returned to the compressor unit of the hermetically sealed vessel.
When an amount of the refrigerator oil which is carried over to the cycle in this way, is increased, there pose problems of a reduction in a heat exchange rate at a heat exchanger, insufficient feeding of oil to the bearing portion, the compressor unit or the like, and so on.
Further, according to the structure disclosed in JP-A-63-21385, mentioned above, the refrigerant delivered from the discharge port passes through single ones of a through hole installed in the compressor unit, the flow guide plate and the oil separator, reaches the oil storage portion installed at the lower portion of the hermetically sealed vessel, passes through the second oil separator therefrom and reaches a space between the block and the stator. Further, the refrigerant is constituted to flow out from the space into the refrigerating cycle via the discharge pipe.
In this way, according to the conventional technology, there poses a problem in which since the passage for passing the refrigerant in the hermetically sealed vessel is restricted, pressure loss is increased and when the structure is used as a compressor for a refrigerating cycle, the efficiency of the refrigerating cycle is lowered.